Switching power converters produce electromagnetic interference (EMI) at the converter switching frequency and harmonics thereof. The EMI may be injected onto conductors connecting the switching power converter to a power source, such as a battery, and affect other devices connected by the power source. To reduce the effects of EMI, an EMI filter may be connected to the power inputs of the switching power converter.
Passive and active type EMI filters are implemented in various applications. Passive EMI filters employ only passive components and can be large and expensive. Active EMI filters employ active components, and can be smaller and more cost effective than passive EMI filters.